U.S. patent number 11,342,302 [Application Number 16/264,957] was granted by the patent office on 2022-05-24 for bonding with pre-deoxide process and apparatus for performing the same.
This patent grant is currently assigned to Taiwan Semiconductor Manufacturing Company, Ltd.. The grantee listed for this patent is Taiwan Semiconductor Manufacturing Company, Ltd.. Invention is credited to Yi-Li Hsiao, Ching-Hua Hsieh, Ying-Jui Huang, Chien Ling Hwang, Tung-Liang Shao, Chih-Hang Tung, Su-Chun Yang, Chen-Hua Yu.
United States Patent |
11,342,302 |
Yu , et al. |
May 24, 2022 |
Bonding with pre-deoxide process and apparatus for performing the
same
Abstract
A method includes picking up a first package component, removing
an oxide layer on an electrical connector of the first package
component, placing the first package component on a second package
component after the oxide layer is removed, and bonding the first
package component to the second package component.
Inventors: |
Yu; Chen-Hua (Hsinchu,
TW), Huang; Ying-Jui (Zhubei, TW), Tung;
Chih-Hang (Hsinchu, TW), Shao; Tung-Liang
(Hsinchu, TW), Hsieh; Ching-Hua (Hsinchu,
TW), Hwang; Chien Ling (Hsinchu, TW),
Hsiao; Yi-Li (Hsinchu, TW), Yang; Su-Chun
(Hsinchu, TW) |
Applicant: |
Name |
City |
State |
Country |
Type |
Taiwan Semiconductor Manufacturing Company, Ltd. |
Hsinchu |
N/A |
TW |
|
|
Assignee: |
Taiwan Semiconductor Manufacturing
Company, Ltd. (Hsinchu, TW)
|
Family
ID: |
1000006324766 |
Appl.
No.: |
16/264,957 |
Filed: |
February 1, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20190326251 A1 |
Oct 24, 2019 |
|
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62660314 |
Apr 20, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L
25/50 (20130101); H01L 24/75 (20130101); H01L
21/4864 (20130101); H01L 21/4853 (20130101); H01L
24/81 (20130101); H01L 2224/7501 (20130101); H01L
2224/81024 (20130101); H01L 2224/81013 (20130101); H01L
2224/81091 (20130101); H01L 2224/757 (20130101); H01L
2224/8109 (20130101); H01L 21/6838 (20130101); H01L
2224/7565 (20130101); H01L 2224/812 (20130101); H01L
2224/81908 (20130101) |
Current International
Class: |
H01L
21/48 (20060101); H01L 23/00 (20060101); H01L
25/00 (20060101); H01L 21/683 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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Apr 2015 |
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112007001365 |
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May 2009 |
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DE |
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2010267895 |
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Nov 2010 |
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JP |
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2014032985 |
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Feb 2014 |
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JP |
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101113438 |
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Feb 2012 |
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KR |
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20120034786 |
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Apr 2012 |
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KR |
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200807591 |
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Feb 2008 |
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TW |
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201407696 |
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Feb 2014 |
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201718163 |
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Jan 2015 |
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WO |
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2017057651 |
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Apr 2017 |
|
WO |
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Primary Examiner: Nguyen; Thanh T
Attorney, Agent or Firm: Slater Matsil, LLP
Parent Case Text
PRIORITY CLAIM AND CROSS-REFERENCE
This application claims the benefit of the following provisionally
filed U.S. Patent application: Application Ser. No. 62/660,314,
filed on Apr. 20, 2018, and entitled "Bonding with Pre-Deoxide
Process and Apparatus for Performing the Same," which application
is hereby incorporated herein by reference.
Claims
What is claimed is:
1. A method comprising: picking up a first package component,
wherein the first package component comprises an electrical
connector, and wherein the electrical connector is oxidized by
nature oxidation to form an oxide layer that comprises a metal
oxide on a surface of the electrical connector; removing the oxide
layer on the electrical connector of the first package component;
after the oxide layer is removed, placing the first package
component on a second package component; and bonding the first
package component to the second package component.
2. The method of claim 1 further comprising transferring the first
package component to the second package component, wherein the
removing the oxide layer is performed during a period of time when
the first package component is transferred to the second package
component.
3. The method of claim 1, wherein the removing the oxide layer
comprises: generating plasma from a forming gas; and after the
first package component is picked up and before the first package
component is placed on the second package component, treating the
first package component with the plasma.
4. The method of claim 1, wherein the removing the oxide layer
comprises: bringing the first package component close to the second
package component; and injecting a plasma of a forming gas into a
gap between the first package component and the second package
component.
5. The method of claim 1, wherein the removing the oxide layer
comprises: scanning the first package component and a plurality of
additional package components with a plasma of a forming gas,
wherein the first package component is identical to the plurality
of additional package components.
6. The method of claim 1, wherein the removing the oxide layer
comprises: before the first package component is picked up,
treating the first package component and a plurality of additional
package components with a plasma of a forming gas, wherein the
first package component and the plurality of additional package
components are treated simultaneously in a vacuum environment.
7. The method of claim 1, wherein the removing the oxide layer
comprises: before the first package component is picked up,
treating the first package component and a plurality of additional
package components with a vapor-phase reductant, wherein the first
package component and the plurality of additional package
components are treated simultaneously in a negative-pressure
environment.
8. The method of claim 1, wherein the electrical connector
comprises copper or tin, and wherein the oxide layer comprises a
copper oxide or a tin oxide.
9. A method comprising: picking up a first package component;
transporting the first package component toward a second package
component; with the first package component being picked up,
removing a metal oxide layer on a surface of an electrical
connector of the first package component; after the metal oxide
layer is removed, placing the first package component onto the
second package component; and heating the first package component
and the second package component to bond the first package
component to the second package component.
10. The method of claim 9 wherein the removing the metal oxide
layer comprises: conducting a plasma of a forming gas to the metal
oxide layer to reduce the metal oxide layer back to metal.
11. The method of claim 10, wherein the removing the metal oxide
layer comprises: stopping movement of the first package component,
with the plasma being conducted to the metal oxide layer when the
first package component is kept still.
12. The method of claim 10, wherein the removing the metal oxide
layer comprises conducting the plasma to the metal oxide layer when
the first package component is moving.
13. The method of claim 12 further comprising moving a plasma
output device along with the first package component to conduct the
plasma to the metal oxide layer when the first package component is
moving.
14. The method of claim 10, wherein the first package component is
picked up using a vacuum head, and the metal oxide layer is removed
when the first package component is on the vacuum head.
15. A method comprising: bring a first package component to a
second package component, with first conductive features in the
first package component facing second conductive features in the
second package component; introducing plasma generated from a
forming gas into a gap between the first package component and the
second package component, wherein the forming gas comprises
hydrogen (H.sub.2) and nitrogen (N.sub.2), and wherein the plasma
contacts both of the first conductive features and the second
conductive features; performing an alignment process to align the
first conductive features to the second conductive features; and
bonding the first conductive features to the second conductive
features.
16. The method of claim 15, wherein oxide layers are on the first
conductive features and the second conductive features before the
plasma is introduced, and wherein the oxide layers are removed by
the plasma.
17. The method of claim 15, wherein the plasma is introduced at a
time before the alignment process is started.
18. The method of claim 15, wherein the plasma is introduced at a
same time the alignment process is performed.
19. The method of claim 15, wherein the gap has a height in a range
between about 1 mm and about 5 mm.
20. The method of claim 15, wherein the plasma is generated at a
pressure equal to one atmosphere.
Description
BACKGROUND
Bonding is a commonly used process for integrating a plurality of
pre-formed package components together. In the bonding process, the
electrical connectors of a first package component are bonded to
the electrical connectors of a second package component to
electrically inter-couple the devices in the first and the second
package components. In an example of the bonding process, a top die
is picked up from a sawed top wafer, and the electrical connectors
of the top die are dipped in a de-oxide agent such as flux. The top
die is then aligned to a bottom die in a bottom wafer, and is
placed on the bottom wafer. The top electrical connectors of the
top die are aligned to and placed over the bottom electrical
connectors in the bottom die. After a plurality of top dies are
placed on the bottom dies, a reflow is performed, so that solder
regions on either the top dies or bottom dies are molten. The
electrical connectors, before bonding, typically have oxides at the
surface. During the reflow, the de-oxide agent removes the oxide on
the top and bottom electrical connectors. After the reflow, the
de-oxide agent is removed, for example, using a solvent or
water.
In another bonding process, after the top dies are placed on the
bottom dies, instead of dipping the top electrical connectors, a
forming gas such as hydrogen is conducted to the top dies and the
bottom dies at the same time the reflow is performed, so that the
oxides may be reduced back to metal.
BRIEF DESCRIPTION OF THE DRAWINGS
Aspects of the present disclosure are best understood from the
following detailed description when read with the accompanying
figures. It is noted that, in accordance with the standard practice
in the industry, various features are not drawn to scale. In fact,
the dimensions of the various features may be arbitrarily increased
or reduced for clarity of discussion.
FIGS. 1 through 4 illustrate the cross-sectional views of
intermediate stages in a bonding process and the corresponding
de-oxide processes in accordance with some embodiments.
FIG. 5 illustrates the block diagrams of a bonder in accordance
with some embodiments.
FIGS. 6 through 9 illustrate the cross-sectional views of
intermediate stages in a bonding process and the corresponding
die-form de-oxide process in accordance with some embodiments.
FIG. 10 illustrates the block diagrams of a bonder in accordance
with some embodiments.
FIGS. 11 through 13 illustrate the cross-sectional views of the
intermediate stages in a bonding process and the corresponding
die-form de-oxide process in accordance with some embodiments.
FIG. 14 illustrates the block diagrams of a bonder in accordance
with some embodiments.
FIGS. 15A and 15B illustrate a cross-sectional view and a top view,
respectively, of the intermediate stages in a wafer-form de-oxide
process in accordance with some embodiments.
FIGS. 16A and 16B illustrate a cross-sectional view and a top view,
respectively, of the intermediate stages in a wafer-form de-oxide
process in accordance with some embodiments.
FIGS. 17 through 20 illustrate the cross-sectional views of the
intermediate stages in some wafer-form de-oxide processes in
accordance with some embodiments.
FIG. 21 illustrates a process flow of a bonding process and the
corresponding de-oxide processes in accordance with some
embodiments.
DETAILED DESCRIPTION
The following disclosure provides many different embodiments, or
examples, for implementing different features of the invention.
Specific examples of components and arrangements are described
below to simplify the present disclosure. These are, of course,
merely examples and are not intended to be limiting. For example,
the formation of a first feature over or on a second feature in the
description that follows may include embodiments in which the first
and second features are formed in direct contact, and may also
include embodiments in which additional features may be formed
between the first and second features, such that the first and
second features may not be in direct contact. In addition, the
present disclosure may repeat reference numerals and/or letters in
the various examples. This repetition is for the purpose of
simplicity and clarity and does not in itself dictate a
relationship between the various embodiments and/or configurations
discussed.
Further, spatially relative terms, such as "underlying," "below,"
"lower," "overlying," "upper" and the like, may be used herein for
ease of description to describe one element or feature's
relationship to another element(s) or feature(s) as illustrated in
the figures. The spatially relative terms are intended to encompass
different orientations of the device in use or operation in
addition to the orientation depicted in the figures. The apparatus
may be otherwise oriented (rotated 90 degrees or at other
orientations) and the spatially relative descriptors used herein
may likewise be interpreted accordingly.
De-oxide processes for bonding package components are provided in
accordance with some embodiments. The intermediate stages of
removing oxide layers on electrical connectors are illustrated in
accordance with some embodiments. Some variations of some
embodiments are discussed. Throughout the various views and
illustrative embodiments, like reference numbers are used to
designate like elements. In accordance with some embodiments of the
present disclosure, the oxides on electrical connectors of some
package components are inline-removed prior to placing (and
bonding) the package components onto other package components,
rather than removing the oxides using flux or forming gases after
the package components are placed in contact with one another. This
may solve the problems of removing residue after the bonding
processes for some package structure.
FIGS. 1 through 4 illustrate the cross-sectional views of
intermediate stages in the de-oxide processes and bonding processes
of packages in accordance with some embodiments of the present
disclosure. The processes shown in FIGS. 1 through 4 are also
reflected schematically in the process flow 300 as shown in FIG.
21.
Referring to FIG. 1, a portion of package component 100 is
illustrated. Package component 100 may be a device die, a package
substrate, an interposer, a package, or the like. In accordance
with some embodiments in which package component 100 includes a
device die, package component 100 may include semiconductor
substrate 102, which may be, for example, a silicon substrate, a
silicon germanium substrate, a III-V compound semiconductor
substrate, or the like. Active devices (not shown) may be formed at
a surface of substrate 102, and may include, for example,
transistors, diodes, or the like. Passive devices such as
resistors, capacitors, inductors, or the like may also be formed in
package component 100. Metal lines and vias 106 are formed in
dielectric layers 108, which may include low-k dielectric layers in
accordance with some embodiments. Metal lines and vias 106 and
dielectric layer 108 are shown schematically. Metal lines and vias
106 interconnect the active devices, and may connect the active
devices to the overlying electrical connector 112.
In accordance with alternative embodiments of the present
disclosure, package component 100 is an interposer die, which is
free from active devices therein. Package component 100 may or may
not include passive devices (not shown) such as resistors,
capacitors, inductors, transformers, and the like in accordance
with some embodiments. In accordance with yet alternative
embodiments, package component 100 is a package substrate, which
may include a laminate package substrate, in which laminated
dielectric layers 108 are formed. Conductive traces 106 (which are
schematically illustrated) are embedded in laminated dielectric
layers 108. In accordance with alternative embodiments of the
present disclosure, package component 100 is a build-up package
substrate, which comprises a core (not shown) and conductive traces
(represented by 106) built on the opposite sides of the cores.
Package component 100 may also include Under-Bump-Metallurgy (UBM)
110, on which electrical connector 112 is formed.
In each of the embodiments wherein package component 100 is a
device die, an interposer die, a package substrate, or the like,
there is a surface dielectric layer 108 formed at the surface of
package component 100. In accordance with some embodiments of the
present disclosure, surface dielectric layer 108 is a
silicon-containing a dielectric layer, which may comprise silicon
oxide, silicon oxynitride (SiON), silicon nitride (SiN), or the
like. Electrical connector 112 is formed as a surface feature of
package component 100, and electrical connector 112 may be
electrically coupled to the active devices through metal lines and
vias 106. Electrical connector 112 may also include solder (such as
a Sn--Ag--Cu solder or a Sn--Pb solder) or a non-solder metallic
material such as copper, aluminum, nickel, tungsten, or alloys
thereof. In accordance with some embodiments of the present
disclosure, as illustrated, electrical connector 112 protrudes
beyond the top surface of the surface dielectric layer 108. In
accordance with other embodiments of the present disclosure, the
top surface of the surface dielectric layer 108 and the top surface
of electrical connector 112 are substantially coplanar with each
other. FIG. 1 also illustrates metal oxide layer 114 formed on the
surface of electrical connector 112. Metal oxide layer 114 may be
the native oxide layer that is formed due to the exposure of
electrical connector 112 to open air. Oxide layer 114 may include
tin oxide, copper oxide, or the like, depending on the material of
electrical connector 112.
In accordance with some embodiments in which package component 100
is a device die, surface dielectric layer 108 and electrical
connector 112, which are used for the subsequent bonding, may be on
the front side (the side with the active devices) or the back side
of substrate 102, although FIG. 1 illustrates that surface
dielectric layer 108 and electrical connector 112 are on the front
side of substrate 102.
In accordance with some embodiments of the present disclosure, a
mass oxide-removal process (represented by arrows 22) is performed
to remove oxide layer 114 from package component 100. The
respective process is illustrated as process 302 in the process
flow shown in FIG. 21. Throughout the description, oxide-removal
processes are also referred to as de-oxide processes. The
respective process is also shown in a dashed box in FIG. 21 to
indicate that this process may be performed or may be skipped. In
the mass oxide-removal process, a plurality of discrete package
components 100 are placed close to each other, for example, on a
template or a dicing tape, and the oxide layers on the plurality of
package components 100 are removed in common processes, as will be
discussed in subsequent processes. The plurality of discrete
package components 100 are spaced apart from each other, and may
have identical structures. The mass oxide-removal process is also
referred to as a wafer-form de-oxide process since a plurality of
package components sawed from a wafer may undertake the same
de-oxide process together. The details of the wafer-form de-oxide
process are also discussed in subsequent paragraphs and shown in
subsequent figures.
FIG. 2 illustrates the pickup and the transfer of package component
100. The respective process is illustrated as process 304 in the
process flow shown in FIG. 21. The pickup process and the transfer
process may be achieved through vacuum head 20. In accordance with
some embodiments of the present disclosure, instead of having the
oxide layers removed in a wafer-form de-oxide process, the oxide
layers 114 (FIG. 1) may be removed in the die-form and during the
transferring of package component 100. The respective process is
illustrated as process 306 in the process flow shown in FIG. 21.
The respective process is also shown in a dashed box to indicate
that this process may be performed or may be skipped. The
corresponding de-oxide process (shown by arrows 24 in FIG. 2) is
referred to as a die-form de-oxide process since in the de-oxide
process, oxide is removed from a single package component 100
rather than from a plurality of package components 100. The details
of the die-form de-oxide process are also discussed in subsequent
paragraphs and shown in subsequent figures.
FIG. 3 illustrates the alignment of package component 100 to
package component 200. The respective process is illustrated as
process 308 in the process flow shown in FIG. 21. Package component
200 may also be selected from a device die, an interposer die, a
package substrate, and the like. In accordance with some
embodiments of the present disclosure, package component 200
includes substrate 202, surface dielectric layer 208, and metal pad
212. Package component 200 may also include dielectric layers
and/or metal lines and vias in the dielectric layers. Package
component 200 may include or free from active devices and/or
passive devices. For example, package component 200 may have a
structure similar to what is described for package component 100,
and the details are not repeated herein. In accordance with some
embodiments of the present disclosure, as illustrated, electrical
connector 212 is recessed from the top surface of surface
dielectric layer 208. In accordance with some embodiments of the
present disclosure, the top surface of surface dielectric layer 208
and the top surfaces of electrical connector 212 are substantially
level with each other.
In accordance with some embodiments of the present disclosure,
surface dielectric layer 208 is a silicon-containing dielectric
layer, which may comprise silicon oxide, SiON, SiN, or the like.
Electrical connector 212 is formed as a surface feature of package
component 200 and may be electrically coupled to active devices (if
formed) in package component 200. Electrical connector 212 may also
include solder (such as a Sn--Ag--Cu solder or a Sn--Pb solder) or
a non-solder metallic material such as copper, aluminum, nickel,
tungsten, or alloys thereof.
In accordance with some embodiments of the present disclosure,
package component 200 is a part of unsawed larger package component
such as an unsawed device wafer, an unsawed interposer wafer, an
unsawed package substrate strip, or a reconstructed wafer with a
plurality of identical device dies packaged therein. In accordance
with other embodiments of the present disclosure, package component
200 is a discrete device die, a discrete interposer, a discrete
package substrate, or the like. A de-oxide process may be performed
to remove the oxide layers on electrical connector 212 prior to the
alignment process. The de-oxide process of package component 200
may be performed, for example, using a wet cleaning process or a
mass de-oxide process as discussed in the present disclosure.
In accordance with some embodiments of the present disclosure, the
oxide layers on both electrical connectors 112 and 212 are removed
simultaneously. The respective process is illustrated as process
310 in the process flow shown in FIG. 21. The respective process is
also shown in a dashed box to indicate that this process may be
performed or may be skipped. The corresponding de-oxide process is
also a die-form de-oxide process since oxide is removed from a
single package component 100 and a single package component 200
rather than from a plurality of package components 100 and/or 200.
The corresponding de-oxide process is represented by arrow 26 in
FIG. 3. For example, package component 100 may be placed close to,
and still spaced apart from, package component 200. The de-oxide
process is then performed, for example, by generating plasma from a
forming gas, which may include a mixture of hydrogen (H.sub.2) and
nitrogen (N.sub.2). The plasma is conducted into the gap between
package components 100 and 200 to reduce the metal oxide layers on
electrical connectors 112 and 212 back to metal. Throughout the
description, the terms "reduce" and "reduction" of metal oxides
mean that in the reduction, the oxygen bonded with metal to form
metal oxides are de-bonded, and the metal atoms become elemental
atoms and remain on the surfaces of electrical connectors 112 and
212. As a result of the reduction, the oxygen atoms previously
bonded with metal may react with hydrogen to form water (H.sub.2O),
which is then evacuated.
Referring to FIG. 4, package component 100 is placed on package
component 200. In accordance with some embodiments of the present
disclosure, the processes shown in FIGS. 1 through 3 are repeated,
so that a plurality of package components 100 are placed on a
plurality of corresponding package components 200. The repetition
of the processes is represented by arrow 311 in the process flow as
shown in FIG. 21. An anneal process or a reflow process is
performed to bond package components 100 to package components 200.
The respective processes are shown as process 312 in the process
flow show in FIG. 21. The interval between the de-oxide processes
22, 24, and 26 (FIGS. 1 through 3) and the time the bonding occurs
is kept short to prevent oxide from being regenerated on the
surfaces of electrical connectors 112 and 212. For example, the
interval may be in the range between about 1 second and about 5
seconds. Also, during the placement of package component 100,
package components 100 and 200 may be located in an environment
with at least reduced oxygen and moisture content, which
environment may be a vacuum environment, a chamber or room filled
with nitrogen, or the like. Alternatively, during the placement of
package component 100, package components 100 and 200 are located
in open (clean) air.
The bonding may include solder bonding, in which either one or both
of electrical connectors 112 and 212 are solder regions, which are
reflowed in the bonding process. In accordance with other
embodiments, the bonding includes metal-to-metal direct bonding, in
which both electrical connectors 112 and 212 are non-solder metal
regions, and the bonding is achieved through the inter-diffusion of
electrical connectors 112 and 212. In accordance with some
embodiments of the present disclosure, surface dielectric layer 108
is bonded to surface dielectric layer 208, for example, through
fusion bonding, in which Si--O--Si bonds may be generated to bond
surface dielectric layers 108 and 208 together. The respective
bonding is thus a hybrid bonding process including both the
metal-to-metal (or solder) bonding and the fusion bonding. In
accordance with other embodiments, surface dielectric layer 108 is
in contact with, and not bonded to, surface dielectric layer 208.
In accordance with yet other embodiments of the present disclosure,
surface dielectric layer 108 is spaced apart from surface
dielectric layer 208 after the bonding.
In the preceding bonding process, oxide can be removed in at least
one or more of the three processes 22 (FIG. 1), 24 (FIGS. 2), and
26 (FIG. 3). These de-oxide processes are all performed before the
bonding of package component 100 to package component 200, and are
also performed before package component 100 is placed on package
component 200. The removal of oxide before the bonding and the
placement has some advantageous features. For example, referring to
the bonded package components 100 and 200, after the bonding
processes, electrical connectors 112 and 212 are either fully
sealed, or the gap for accessing electrical connectors 112 and 212
is very small. If flux is used to remove oxides from electrical
connectors 112 and 212, the flux needs to be removed after the
bonding, which is either impossible or very difficult since the
flux may be sealed or the access channel is too small. In
accordance with some embodiments of the present disclosure, the
de-oxide process is performed before the bonding, and hence no flux
removal process is needed after the bonding process.
FIGS. 5 through 21 illustrate the apparatus and the processes for
performing the de-oxide processes and the subsequent bonding
process in accordance with some embodiments. FIG. 5 illustrates the
apparatus for performing the die-form de-oxide process as shown in
FIG. 2 in accordance with some embodiments of the present
disclosure, and FIGS. 6 through 9 illustrate the cross-sectional
views of the corresponding processes.
FIG. 5 illustrates apparatus 400A for performing the bonding
process as illustrated in FIGS. 1 through 4. The apparatus 400A is
also referred to as a bonder. Bonder 400A is used for performing a
de-oxide process from package component 100 (FIG. 2) in die-form,
and then bonding the package components. In accordance with some
embodiments of the present disclosure, bonder 400A includes pickup
module 402, de-oxide module 404A, alignment module 406, and
placement module 408. Each of the pickup module 402, de-oxide
module 404A, alignment module 406, and placement module 408
includes the corresponding hardware. Also, software may be provided
for controlling the hardware. For example, controller 410 (which
includes hardware and software) is signally connected to, and is
configured to control and coordinate the operations of, pickup
module 402, de-oxide module 404A, alignment module 406, placement
module 408, and other tools in bonder 400A. Pickup module 402 is
used for picking up and transferring package components 100 (FIG.
2), and may be used for flipping package components 100 if needed.
De-oxide module 404A is used for removing the oxide from package
components. Alignment module 406 is used for aligning (FIG. 3)
package components that are to be bonded together. Placement module
408 is used for placing package components 100 onto other package
components 200 (FIG. 4).
The operation of components in bonder 400A is discussed in detail
referring to the process as shown in FIGS. 6 through 9. It is
appreciated that FIGS. 6 through 9 show the same processes as in
FIGS. 1 through 4, except that FIGS. 1 through 4 concentrate on the
structural details of package components, and FIGS. 6 through 9
concentrate on the details of the de-oxide process. Referring to
FIG. 6, a plurality of package components 100 are placed over
supporting media 28. In accordance with some embodiments of the
present disclosure, supporting media 28 is a dicing tape, on which
a wafer is sawed apart into discrete package components 100. In
accordance with alternative embodiments of the present disclosure,
supporting media 28 is a template, and package components 100 are
sawed on a dicing tape, and then placed on the template for the
pick-and-place process.
Pickup module 402 (FIG. 5) is configured to pick up package
component 100 in FIG. 6. Pickup module 402 may include pickup head
20 (FIG. 6), which may be a vacuum head in accordance with some
embodiments. One of package components 100 is picked up by pickup
head 20. Next, referring to FIG. 7, a de-oxide process is performed
on the package component 100 that has been picked up. FIG. 7
schematically illustrates electrical connectors 112, which are
exposed during the transfer of package component 100.
Plasma generator 30, which is comprised in de-oxide module 404A in
FIG. 5, is schematically illustrated. Plasma generator 30 may
include Radio Frequency (RF) power generator 32, forming gas
source(s) (tanks) (not shown), and plasma output device 34. In
accordance with some embodiments of the present disclosure, plasma
output device 34 includes electrodes that are connected to and
receive RF power from RF power generator 32. The forming gas, which
may include H.sub.2 and N.sub.2 in accordance with some
embodiments, may be conducted between the electrodes, which
generate plasma from the forming gas. The Plasma is blown out to
package component 100 to reduce the metal oxide on package
component 100 back to metal. In accordance with some embodiments of
the present disclosure, the de-oxide process is performed for a
duration in the range between about 100 millisecond and about 5
seconds. The plasma may be atmosphere plasma, which is generated
under the pressure of one atmosphere.
It is appreciated that the plasma generator 30 as illustrated is
merely an example, and other types of plasma generators using
different plasma-generating mechanisms may also be used. For
example, plasma generator 30 may be a remote plasma generator,
which generates the plasma in a location not immediately next to
package component 100, and the remote plasma is conducted to
package component 100.
In accordance with some embodiments of the present disclosure, the
plasma output device 34 is fixed at a location between supporting
media 28 (FIG. 6) and package components 200 (FIG. 8). The package
component 100 picked by the pickup head 20 is moved toward plasma
output device 34, and parked in alignment with plasma output device
34. The de-oxide process is then performed while the package
component 100 is aligned with the plasma output device 34. After
the de-oxide process, package component 100 is transferred again to
package component 200 (FIG. 8). In accordance with alternative
embodiments, plasma output device 34 is movable. During the
transferring of package component 100, vacuum head 20 and plasma
output device 34 are moved in the same direction (as represented by
arrows 36A and 36B), with the movement being synchronized, so that
at the same time package component 100 is transferred, the de-oxide
process is performed. This improves the throughput of the de-oxide
process.
FIG. 8 illustrates the alignment of package component 100 to
package component 200. The alignment is performed by alignment
module 406 as shown in FIG. 5. As shown in detail as in FIG. 3, the
electrical connectors (such as 112 in FIG. 4) of package components
100 are aligned to electrical connectors 212 in package components
200. Package component 100 is then placed on package component 200
by placement module 408 (FIG. 5). The processes as shown in FIGS. 6
through 8 are repeated for each of package components 100.
A bonding process is then performed, as shown in FIG. 9. Depending
on the intended type of bonding, the bonding process may adopt
appropriate time and temperature to reflow solder regions (if any),
or to bring about inter-diffusion between electrical connectors 112
and 212.
FIG. 10 illustrates the block diagram of bonder 400B for performing
the die-form de-oxide process as shown in FIG. 3 in accordance with
some embodiments of the present disclosure, and FIGS. 11 through 13
illustrate the cross-sectional views of the corresponding
processes. Bonder 400B is used for performing a die-form
oxide-removal process for both package components 100 and 200, and
then bonding package components 100 to package components 200. In
accordance with some embodiments of the present disclosure, bonder
400B includes pickup module 402, alignment module 406, placement
module 408, and de-oxide module 404A. Controller 410 is connected
to, and is configured to control and coordinate the operations of,
pickup module 402, alignment module 406, placement module 408,
de-oxide module 404A, and other tools in bonder 400B. The functions
of pickup module 402, alignment module 406, placement module 408,
and de-oxide module 404A are discussed referring to the processes
shown in FIGS. 11, 12, and 13.
Referring to FIG. 11, package components 100 are placed on
supporting media 28. Pickup module 402 (FIG. 10), which may include
vacuum head 20 as in FIG. 11, is used to pickup package components
100 one-by-one and transfer package component 100 to package
component 200. FIG. 12 schematically illustrates the transferring
of package component 100.
FIG. 13 illustrates the alignment and the de-oxide process. The
alignment of package component 100 to package component 200 is
conducted by alignment module 406 as shown in FIG. 10. The de-oxide
process is conducted by de-oxide module 404A as shown in FIG. 10.
De-oxide module 404A includes plasma generator 30, which may
include plasma output device 34. In accordance with some
embodiments of the present disclosure, package component 100 is
held at a short distance DS1 from package component 200. Distance
DS1 is small to improve the efficiency in the de-oxide process. For
example, distance DS1 may be in the range between about 1 mm and
about 5 mm. Plasma output device 34 is aimed at the gap between
package components 100 and 200. With package component 100 being
held over package component 200, the plasma generated from the
forming gas is blown into the gap, so that the metal oxides on the
electrical connectors of package components 100 and 200 are reduced
back to metal. The plasma may be atmosphere plasma, which is
generated under the pressure of one atmosphere. In accordance with
some embodiments of the present disclosure, the de-oxide process is
performed for a duration in the range between about 100 millisecond
and about 5 seconds.
In accordance with some embodiments of the present disclosure, the
de-oxide process is performed before aligning package component 100
to package component 200. In accordance with alternative
embodiments of the present disclosure, the de-oxide process is
performed after aligning package component 100 to package component
200. The de-oxide process may also be performed at the same time
package component 100 is being aligned to package component 200. In
accordance with other embodiments, the de-oxide process may include
any combination of the periods of time before, during, and after
the alignment. Package component 100 is then placed on package
component 200 by placement module 408 (FIG. 10). A bonding process
is then performed. Depending on the intended type of bonding, the
bonding process may adopt appropriate time and temperature to
reflow solder regions (if any), or to incur inter-diffusion between
electrical connectors 112 and 212. The resulting structure is shown
in FIG. 9, and hence the details are not discussed herein.
In accordance with some embodiments of the present disclosure,
during the transferring (FIG. 12) of package component 100, no
de-oxide process is performed. In accordance with other embodiments
of the present disclosure, the de-oxide process is performed both
during the transferring process as shown in FIG. 12, and in the
step as shown FIG. 13. Accordingly, plasma output device 34 may
move along with package component 100 similar to what is shown in
FIG. 7, and then is stopped at the position shown in FIG. 13 to
further conduct the de-oxide process. This may improve the
throughput of the bonding process.
FIG. 14 illustrates the block diagram of bonder 400C for performing
the wafer-form de-oxide process 22 (FIG. 1) in accordance with some
embodiments. Bonder 400C is used for performing the wafer-form
oxide-removal process for package components 100, and then bonding
the package components. In accordance with some embodiments of the
present disclosure, bonder 400C includes de-oxide module 404B,
pickup module 402, alignment module 406, and placement module 408.
Controller 410 is connected to, and is configured to control and
coordinate the operation of, de-oxide module 404B, pickup module
402, alignment module 406, placement module 408, and other tools in
bonder 400.
FIGS. 15A and 15B illustrate the cross-sectional view and top view,
respectively, of a wafer-form de-oxide process in accordance with
some embodiments. The respective process is illustrated as process
302 as shown in FIG. 21 and by arrows 22 in FIG. 1. In the
wafer-form oxide-removal process, the oxides on the electrical
connectors of a plurality of package components 100 are removed in
the same process. In accordance with some embodiments of the
present disclosure, de-oxide module 404B (FIG. 14) includes plasma
generator 30, which may further include RF generator 32 and plasma
output device 34. The plasma may be atmosphere plasma, which is
generated under the pressure of one atmosphere. Package components
100 are located on supporting media 28 (FIG. 15A), and may be
aligned into an array including a plurality of rows and columns.
The outlet of plasma output device 34 may be an elongated slot that
extends on one or a plurality of package components 100. For
example, FIG. 15B illustrates a top view of a portion of plasma
output device 34 in accordance with some embodiments. The
illustrated plasma output device 34 may have an elongated outlet.
For example, the width W1 of the outlet may be in the range between
about 0.5 mm and about 2 mm. The length L1 of the outlet may be in
the range between about 10 mm and about 40 mm. Arrow 38 represents
the movement of plasma output device 34. With the movement of
plasma output device 34, package components 100 are scanned, with
the corresponding electrical connectors de-oxidized. Plasma output
device 34 may scan line-by-line to cover all of the package
components 100 on supporting media 28.
FIGS. 16A and 16B illustrate a cross-sectional view and a top view,
respectively, of plasma output device 34 as well as the
corresponding de-oxide process in accordance with some embodiments.
The respective de-oxide process is also illustrated as process 302
as shown in FIG. 21 and by arrows 22 in FIG. 1. Plasma output
device 34 may be a part of the de-oxide module 404B as shown in
FIG. 15. Referring to FIG. 16B, plasma channel 40 is used for
outputting the plasma. Exhaust channel 42 is formed on the outer
side of plasma channel 40. Exhaust channel 42 may form a full ring
encircling plasma channel 40. On the outer side of exhaust channel
42 is inert gas channel 44. Inert gas channel 44 may form a full
ring encircling exhaust channel 42. Channels 40, 42, and 44 are
separated from each other. A first sidewall 40A, which may be a
first ring in the top view, defines plasma channel 40. A second
sidewall 42A, which may form a second ring in the top view, defines
exhaust channel 42 along with the first sidewall 40A. A third
sidewall 44A, which may form a third ring in the top view, defines
inert gas channel 44 along with the second sidewall 42A.
FIG. 16A illustrates the cross-sectional view of the process as
shown in FIG. 16B. The plasma (represented by arrow 46) for
reducing the metal oxide is conducted toward package component 100.
Inert gas channel 44 is used to conduct an inert gas such as
nitrogen, argon, or the like. The inert gas is represented by arrow
48. The inner gas 48 acts as a barrier for the plasma and the
corresponding forming gas, so that the forming gas does not escape
to the outside environment. Exhaust channel 42 is used to recycle
the inert gas and the forming gas, which are represented by arrows
50. For example, pump 52 may be connected to the outlet of exhaust
channel 42 to pump gases 50 out.
In accordance with some embodiments of the present disclosure,
outer sidewall 44A has bottom edge 44A-BE at a level slightly
higher than the top surfaces of package components 100. Sidewalls
40A and 42A also have bottom ends higher than the top surface of
package components 100. Accordingly, plasma output device 34 may
scan through package components 100 without having to go up and
down. The vertical distance DS2 between bottom end 44A-BE and the
top surface of package components 100 may be smaller than about 2
mm, and may be in the range between about 1 mm and about 2 mm. In
accordance with alternative embodiments of the present disclosure,
bottom ends 44A-BE of outer sidewall 44A are lower than the top
surfaces of package components 100. Accordingly, as shown in FIG.
16B, inert gas channel 44 is sized and shaped to receive at least
one, and possibly more package components 100 therein. In the
corresponding de-oxide process, plasma output device 34 is moved
over some package components 100, and is then lowered until the
bottom edge 44A-BE is lower than the top surfaces of the
corresponding package components 100 so that the package components
100 are received within the inert gas channel 44. The de-oxide
process is then performed on the corresponding package components.
After the de-oxide process is finished. Plasma output device 34 is
raised, and then moved to the neighboring package components 100 to
perform the de-oxide process. This process is repeated until all of
the package components are de-oxidized. The de-oxide process as
shown in FIGS. 16A and 16B may be performed in an environment with
a pressure of one atmosphere.
FIG. 17 illustrates a cross-sectional view of a wafer-form de-oxide
process in accordance with some embodiments. The respective
de-oxide process is also illustrated as process 302 as shown in
FIG. 21 and by arrows 22 in FIG. 1. This process may be performed
by generating plasma 58 in vacuum, which vacuum is generated by
pump 54. The de-oxide process is performed in chamber 55, which may
have a pressure lower than about 10 mTorr. Shower head 56 is used
to output plasma 58, which is generated by RF generator 32 using a
forming gas, for example. Shower head 56 and RF generator 32 may be
the parts of the de-oxide module 404B as shown in FIG. 15. The
electrical connectors in a plurality of package components 100 are
de-oxidized simultaneously by plasma 58. In accordance with some
embodiments of the present disclosure, the duration of the de-oxide
process is in the range between about 1 second to 10 seconds.
FIG. 18 illustrates a cross-sectional view of a wafer-form de-oxide
process and the corresponding de-oxide module 404B in accordance
with some embodiments. The respective de-oxide process is also
illustrated as process 302 as shown in FIG. 21 and by arrows 22 in
FIG. 1. This process may be performed through conducting
vapor-phase reductant (such as citric acid) or a forming gas into
chamber 59. Chamber 59 is maintained under a pressure slightly
lower than one atmosphere. For example, the pressure in chamber 59
is lower than about 0.9 atmospheres. The gases in chamber 59 may be
exhausted through channel 66. When the vapor-phase reductant is
used, bubbler 60 may be used to generate the vapor-phase reductant
from a liquid-phase reductant 61. The vapor-phase reductant or the
forming gas may be conducted through shower head 63 to reduce the
oxide in package components 100 back to metal.
FIGS. 19 and 20 illustrate the cross-sectional views of
intermediate stages in a wafer-form de-oxide process and the
corresponding de-oxide module 404B in accordance with some
embodiments. The respective de-oxide process is also illustrated as
process 302 as shown in FIG. 21 and by arrows 22 in FIG. 1. This
process may be performed through spraying flux 68 onto package
components 100 using spray nozzle 62, and heating the package
components 100. The flux is activated by the heat to remove the
oxides on package components 100. Spray nozzle 62 scans through all
package components 100, so that all of package components 100 are
sprayed with the flux 68. In accordance with some embodiments of
the present disclosure, after all package components 100 are
sprayed with the flux, package components 100 are heated to a
temperature in the range between about 60.degree. C. and about
70.degree. C. The heating duration may be in the range between
about 30 seconds and about 5 minutes. After the heating, as shown
in FIG. 20, spray nozzle 64 scans through all package components
100 again and spray cleaning fluid 70, which may be de-ionized
water or a chemical solution, so that the residue of the flux is
removed.
The wafer-form de-oxide process may be performed using any of the
apparatus and processes in FIGS. 15A and 15B, FIGS. 16A and 16B,
FIG. 17, FIG. 18, and FIGS. 19 and 20. After the wafer-form
de-oxide process, package components 100 are picked up by pickup
module 402 (FIG. 14). An alignment is then performed to align
package component 100 with the underlying package component 200
(refer to FIG. 4). The alignment is performed by the alignment
module 406 (FIG. 14). Next, the placement module 408 as shown in
FIG. 14 places package component 100 on package component 200
(refer to FIGS. 4 and 8). The pick-and-place process is repeated,
so that a plurality of package components 100 are placed on a
plurality of package components 200. An anneal/reflow process is
then performed to bond package components 100 with package
components 200.
The embodiments of the present disclosure have some advantageous
features. By performing the de-oxide process before the placement
and the bonding of package components, the bonded package
components do not need to be cleaned to remove the residue of flux.
This advantageously improves the reliability of some packages
because some of the packages, due to their structures, are
difficult to have the flux residue removed. Also, the embodiments
of the present disclosure solve the problem that forming gas (if
used) cannot be conducted to electrical connectors to de-oxide
during the bonding process.
In accordance with some embodiments of the present disclosure, a
method includes picking up a first package component; removing an
oxide layer on an electrical connector of the first package
component; after the oxide layer is removed, placing the first
package component on a second package component; and bonding the
first package component to the second package component. In an
embodiment, the method further includes transferring the first
package component to the second package component, wherein the
removing the oxide layer is performed during a period of time when
the first package component is transferred to the second package
component. In an embodiment, the removing the oxide layer
comprises: generating plasma from a forming gas; and after the
first package component is picked up and before the first package
component is placed on the second package component, treating the
first package component with the plasma. In an embodiment, the
removing the oxide layer comprises: bringing the first package
component close to the second package component; and injecting a
plasma of a forming gas into a gap between the first package
component and the second package component. In an embodiment, the
removing the oxide layer comprises: scanning the first package
component and a plurality of additional package components with a
plasma of a forming gas, wherein the first package component is
identical to the plurality of additional package components. In an
embodiment, the removing the oxide layer comprises: before the
first package component is picked up, treating the first package
component and a plurality of additional package components with a
plasma of a forming gas, wherein the first package component and
the plurality of additional package components are treated
simultaneously in a vacuum environment. In an embodiment, the
removing the oxide layer comprises: before the first package
component is picked up, treating the first package component and a
plurality of additional package components with a vapor-phase
reductant, wherein the first package component and the plurality of
additional package components are treated simultaneously in a
negative-pressure environment. In an embodiment, the removing the
oxide layer comprises: spraying the first package component and a
plurality of additional package components with a flux; heating the
first package component and the plurality of additional package
components simultaneously to remove the oxide layer; and cleaning a
residue of the flux.
In accordance with some embodiments of the present disclosure, a
method includes picking up a first package component; transporting
the first package component toward a second package component; with
the first package component being picked up, removing a metal oxide
layer on a surface of an electrical connector of the first package
component; after the metal oxide layer is removed, placing the
first package component onto the second package component; and
heating the first package component and the second package
component to bond the first package component to the second package
component. In an embodiment, the removing the metal oxide layer
comprises: conducting a plasma of a forming gas to the metal oxide
layer to reduce the metal oxide layer back to metal. In an
embodiment, the removing the oxide layer comprises: stopping
movement of the first package component, with the plasma being
conducted to the metal oxide layer when the first package component
is kept still. In an embodiment, the removing the oxide layer
comprises conducting the plasma to the metal oxide layer when the
first package component is moving. In an embodiment, the method
further includes moving a plasma output device along with the first
package component to conduct the plasma to the metal oxide layer
when the first package component is moving. In an embodiment, the
first package component is picked up using a vacuum head, and the
oxide layer is removed when the first package component is on the
vacuum head.
In accordance with some embodiments of the present disclosure, an
apparatus configured to bond a first package component to a second
package component includes a pickup module configured to pick up
the first package component; a de-oxide module configured to remove
an oxide layer from the first package component; an alignment
module configured to align the first package component to the
second package component; and a placement module configured to
place the first package component on the second package component.
In an embodiment, the apparatus further includes a controller
signally connected to, and is configured to control operations of,
the pickup module, the de-oxide module, the alignment module, and
the placement module. In an embodiment, the de-oxide module
comprises a plasma output device configured to output plasma toward
the first package component. In an embodiment, the plasma output
device is configured to output the plasma toward the first package
component after the first package component is picked up. In an
embodiment, the plasma output device is configured to output the
plasma when moving in a mode synchronized with a movement of the
first package component. In an embodiment, the de-oxide module is
configured to perform a de-oxide operation on a plurality of
package components.
The foregoing outlines features of several embodiments so that
those skilled in the art may better understand the aspects of the
present disclosure. Those skilled in the art should appreciate that
they may readily use the present disclosure as a basis for
designing or modifying other processes and structures for carrying
out the same purposes and/or achieving the same advantages of the
embodiments introduced herein. Those skilled in the art should also
realize that such equivalent constructions do not depart from the
spirit and scope of the present disclosure, and that they may make
various changes, substitutions, and alterations herein without
departing from the spirit and scope of the present disclosure.
* * * * *